Adjust to new contagious mutations

[realsnegu]

CWA Open Source Team announcements

The RKI and the development team are closely monitoring the situation concerning the newer virus mutations. As said in the FAQ entry about mutations , the risk calculation will be updated and adjusted as soon as new information is available. We will publish new information on this in the FAQ or here on Github.

Official announcements in our blog:

• 23.02.2021 - Corona-Warn-App’s risk calculation further adjusted after detailed tests
• 19.03.2021 - Corona-Warn-App's risk calculation further improved
• 16.04.2021 - Project Team further improves Corona-Warn-App's risk calculation in response to current coronavirus situation
• 08.07.2021 - Virus variants in the Corona-Warn-App

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Original post

As the new found virus mutant B.1.1.7 comes with significant higher contagiousness there must be an high prio update taking this fact into consideration. I need to spend now fewer time next to an infected person in order to catch covid hence the warning mechanism should be reconsidered and adjusted.

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Internal Tracking ID: EXPOSUREAPP-4571

[MikeMcC399]

@realsnegu

According to https://en.wikipedia.org/wiki/Variant_of_Concern_202012/01 B.1.1.7 is also referred to as Variant of Concern 202012/01 (VOC-202012/01) and RKI have been continually updating their assessment on Informationen zu neuen SARS-CoV-2-Virusvarianten aus Großbritannien und Südafrika. It seems that they are still collecting data.

Do you know about any other data which would allow the risk assessment parameters to be changed?

When a Corona-Warn-App user reports they are infected they can add information regarding onset of symptoms, but there is no mechanism to report what virus strain they are infected with, so the warning mechanism could currently only be changed based on statistical probability. That would be possible if there is data to base any calculations on.

(Reference to current risk assessment is in https://www.coronawarn.app/en/blog/2020-12-17-risk-calculation-exposure-notification-framework-2-0/ or for a more complete discussion, see https://www.coronawarn.app/en/blog/2020-12-30-cwa-behind-the-scenes/.)

[Ein-Tim]

Also relevant: https://www.coronawarn.app/en/faq/#mutation

Related: https://github.com/corona-warn-app/cwa-documentation/issues/507

[heinezen]

Hello @realsnegu ,

The RKI and the development team are closely monitoring the situation concerning the newer virus mutations. As said in the FAQ entry linked by @Ein-Tim , the risk calculation will be updated and adjusted as soon as new information is available. We will publish new information on this in the FAQ or here on Github when it becomes available.

Regards, CH

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Corona-Warn-App Open Source Team

[kosmar]

When a Corona-Warn-App user reports they are infected they can add information regarding onset of symptoms, but there is no mechanism to report what virus strain they are infected with

to get this clear: the app does currently not offer any way to input the strain, even if the lab or user would know the strain? is this planned to be implemented?

thx @MikeMcC399 @realsnegu

[Ein-Tim]

@kosmar

the app does currently not offer any way to input the strain, even if the lab or user would know the strain?

Correct, the user can't input the strain.

[Ein-Tim]

Seems like update will change the sensitivity of the App: https://www.deutschlandfunk.de/wegen-virus-mutationen-corona-warn-app-schlaegt-kuenftig.1939.de.html?drn:news_id=1230445 or https://www.rnd.de/politik/corona-warn-app-reagiert-kunftig-empfindlicher-auf-risikobegegnungen-V5YHNLDE3KI74EQK5K7AXYZQME.html

[dsarkar]

@Ein-Tim FYI

https://github.com/corona-warn-app/cwa-server/pull/1213/files https://github.com/corona-warn-app/cwa-server/pull/1212/files https://github.com/corona-warn-app/cwa-server/pull/1207/files

[Ein-Tim]

Thanks @dsarkar. So the change will be in 1.13, correct (or is it already live, I'm a bit lost with these branches, sorry)?

[dsarkar]

@Ein-Tim as far as I understand this is life since yesterday, see 1207. But I am gonna ask the developers to make sure.

[Ein-Tim]

@dsarkar

Seems to be live now: https://www.coronawarn.app/en/blog/2021-02-23-corona-warn-app-risk-calculation-optimization/

[heinezen]

Additional request from @Andiadm made here: https://github.com/corona-warn-app/cwa-wishlist/issues/373#issue-816163175

The Infectiousness profile was based on He et al and later updated. Recently a Harvard publication suggest that the mean duration of the proliferation phase was 5.3 days in the B117 variant group vs. 2.0 days for non-B.1.1.7 virus. I wanted to raise this issue because with the B117 becoming more and more widely spread, this finding obviously calls for a change in the profile. Ideally, the CWA would use a differnt profile depending if the positively tested person was infected by B117. This might be a too big change. But I would prefer to produce more warning messages than too little.

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Corona-Warn-App Open Source Team

[Ein-Tim]

There was another improvement to the risk calculation:

English: https://www.coronawarn.app/en/blog/2021-03-19-risk-calculation-improvement/

German: https://www.coronawarn.app/de/blog/2021-03-19-risk-calculation-improvement/

[Ein-Tim]

@dsarkar @heinezen

We now have the "Delta" variant. I assume for this the same goes here, or do you want a new issue for tracking the risk calculation changes that might be necessary because of the "Delta" variant?

[MikeMcC399]

@Ein-Tim RKI continuously monitors Variants of Concern (and Variants of Interest) and publishes a weekly report https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Virusvariante.html about them.

So far RKI has adjusted the risk calculations in CWA according to changes in the situation without prompting, so I don't know if it is necessary to have a separate wishlist item open here for the Delta variant (B.1.617.2). It is really part of RKI's core responsibility to make changes as necessary.

Perhaps the Open Source Team could check if they agree with this?

[ndegendogo]

@MikeMcC399 do you know if the true "productive" configuration parameters (like TRL tables) are always tracked here in the github repo? Or are the configuration parameters here to be seen as "example", but the true config is managed outside of github?

[Ein-Tim]

@ndegendogo Some current risk calculation parameters can be found here: https://github.com/corona-warn-app/cwa-server/blob/main/services/distribution/src/main/resources/main-config/v2/risk-calculation-parameters.yaml

[MikeMcC399]

@ndegendogo You can check what parameters are being used by a production app by using the Error Reports (in Android: three-dot symbol > App Information > Error Reports). The parameters are recorded in the log.

In a debug Android build there is a Test Menu which allows you to view "Remote Config Data".

There was a discussion in https://github.com/corona-warn-app/cwa-server/issues/1346 about where the data comes from, and for current versions of the app using v2 / ExposureWindow mode, one of the sources is https://github.com/corona-warn-app/cwa-server/blob/release/2.0/services/distribution/src/main/resources/main-config/v2/risk-calculation-parameters-1.15.yaml. (The file which @Ein-Tim quoted in the previous comment is only used for legacy v1 mode AFAIK.)

There are some other relevant config files in the directory https://github.com/corona-warn-app/cwa-server/tree/main/services/distribution/src/main/resources/main-config/v2 as well.

As far as I have seen, the parameters always come from a https://github.com/corona-warn-app/cwa-server version branch, however there can be a time-lag between releasing a version on GitHub and going live with it in the production environment. If you want a better answer, you would need to ask in the cwa-server repo exactly how they handle it.

[Ein-Tim]

(The file which @Ein-Tim quoted in the previous comment is only used for legacy v1 mode AFAIK.)

Learned something new again 😉

Thanks @MikeMcC399 🙂

[ndegendogo]

You can check what parameters are being used a production app by using the Error Reports

@MikeMcC399 this is a very useful hint - thanks a lot!! 👍😁

[heinezen]

@Ein-Tim @MikeMcC399 @ndegendogo

The configuration parameters for the risk calculation are fetched independently of the releases (daily I think(?))

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Corona-Warn-App Open Source Team

[Ein-Tim]

@heinezen Thank you for confirming. Could you maybe change the title here to Adjust risk calculation to new virus variants so that we can use this issue not only for the B.1.1.7 variant but also for the Delta variant?

This would be nice, thanks!

[aurisnoctis]

Info from official Australian sources that contact of less than a minute might spread the virus from one person to another. https://twitter.com/DrEricDing/status/1406779894785351688

Delta variant is likely at about 50% in Germany now. https://www.stuttgarter-zeitung.de/inhalt.coronavirus-in-deutschland-rki-jede-zweite-neuinfektion-mit-delta-variante.6e7d28ff-f41f-45df-af2c-d39c624d4879.html

I didn't understand from the information above if this is indeed handled in a timely manner by RKI and if so if they directly work in the cwa-server repo and adapt yaml files such as https://github.com/corona-warn-app/cwa-server/blob/release/2.0/services/distribution/src/main/resources/main-config/v2/risk-calculation-parameters-1.15.yaml, which is then instantly used in production? :thinking:

Thanks in advance for clarification! Wouldn't want to miss a red warning where it's due :red_circle:

[Ein-Tim]

@aurisnoctis

I didn't understand from the information above if this is indeed handled in a timely manner by RKI and if so if they directly work in the cwa-server repo and adapt yaml files such as https://github.com/corona-warn-app/cwa-server/blob/release/2.0/services/distribution/src/main/resources/main-config/v2/risk-calculation-parameters-1.15.yaml, which is then instantly used in production? 🤔

Yes. Any change there which is deployed to the productive server will be fetched from the app and the risk calculation changes.

But, no, the RKI does not directly work in this repo. T-Systems is responsible for the backend of the app.

[aurisnoctis]

configuration parameters for the risk calculation are fetched independently of the releases ... https://github.com/corona-warn-app/cwa-wishlist/issues/328#issuecomment-869154263

Any change there which is deployed to the productive server will be fetched from the app ... https://github.com/corona-warn-app/cwa-wishlist/issues/328#issuecomment-869936770

So "release" in the first quote refers to releases of the Android and iOS client app and "deployed" in the second quote refers to cwa-server, I guess.

The last entry in https://www.coronawarn.app/en/faq/#mutation is from April and says

"... duration of a critical encounter from 13 minutes to 9 minutes." https://www.coronawarn.app/en/blog/2021-04-16-corona-warn-app-risk-calculation-further-improved/

Given information from Australia mentioned in https://github.com/corona-warn-app/cwa-wishlist/issues/328#issuecomment-869934072, this does not seem to be enough reduction in minimum encounter duration.

[MikeMcC399]

RKI confirmed on https://twitter.com/coronawarnapp/status/1410175943679918081?s=20 that they are specifically monitoring the Delta Variant of Concern and that they in general will make changes as necessary based on other VoCs.

https://twitter.com/coronawarnapp/status/1410175943679918081?s=20

"4/x Wird die Delta-Variante berücksichtigt?

Seit Beginn der Pandemie werden neue Virus-Varianten entdeckt und bzgl. Infektiosität und gesundheitlicher Folgen untersucht. Wenn sich nach neuen Erkenntnissen das Infektionsrisiko ändert, passen wir die Risikoberechnung der App an."

[MikeMcC399]

There is a new blog post which specifically also mentions the Delta variant https://www.coronawarn.app/en/blog/2021-07-08-cwa-virus-variants/

It repeats what has previously been stated, that the situation is continuously monitored and that changes will be made if necessary. (They aren't yet considered necessary.)

[heinezen]

@realsnegu I have hijacked your initial post to add the blogpost announcement if that's okay for you.

We will now try to communicate via this thread if there are changes due to Delta or other variants.

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Corona-Warn-App Open Source Team

[aurisnoctis]

There is a new blog post which specifically also mentions the Delta variant https://www.coronawarn.app/en/blog/2021-07-08-cwa-virus-variants/

The Project Team is following the recommendations for action for the "analog" contact tracing of the public health authorities in the risk calculation in the Corona-Warn-App. As soon as there are changes here, the risk calculation in the Corona-Warn-App will also be adapted.

In October 2020, the "analog contact tracing" in Mainz, Germany didn't even warn people that were in the same room with infected people during a 3-hour pub quiz. Luckily, CWA warned the other people in the room though, with a red risk card. When they called the pub, they were informed that only people at the same table would be warned the analog way in the coming days.

I hope CWA continues to be better than the "analog" way, or alternatively that the analog way gets as good as CWA. The red risk card in CWA made PCR testing for the other people that had been in the room possible without hassle. They never heard from the health authorities and frankly didn't need them in this case.

[realsnegu]

@heinezen totally fine with it. I'm just following the comments silently and am happy that the CWA is developing further.

[gittaca]

Um mal aus https://github.com/corona-warn-app/cwa-wishlist/issues/352 zu zitieren

Seine Meinung scheint durch ‚hochrangige’ Gäste oftmals bestärkt zu werden, die etwas süffisant erzählen, sie würden (als Prof. Dr.) auf einer Corona-Station arbeiten, täglich mit Corona-Patienten zu tun haben..., aber ihre App zeige immer nur grün – also kein Risiko.

Das wäre ein Problem, das auch durch Anpassung der Parameter mitverhindert werden könnte.